This invention relates to methods and apparatus to displace an organ from an adjacent anatomic structure and thereafter retract, orient, manipulate or stabilize it for further surgical procedures. The devices include an inflatable manipulator and various positioning and anchoring structures and tools to allow optimal placement of the manipulator in the desired anatomic location. Once in place, the manipulator is inflated to properly position the organ for surgery. The manipulator may optionally be used during surgery to dissect, cool or monitor the status of organs. The devices and methods disclosed herein are particularly suited for cardiac surgery.
The last half of the 20th Century has seen the birth and evolution of both open cardiac surgery as well as minimally invasive surgery (MIS) applied to a wide variety of procedures. Until recently, however, the two surgical specialties evolved largely independently. The complexity of the cardiac procedures, the potential for sudden and catastrophic complications, and the lack of effective tools to provide optimal surgical access inhibited development of MIS techniques.
Although open heart surgery has been employed to treat heart disease, most often it has been applied to reestablishing blood supply to the heart muscle itself. The principle objective is either to clear occluded arteries or to graft replacement vessels around the blockages. In the latter case, these coronary artery bypass graft (CABG) procedures are generally effective, but only for a limited time, usually a few to ten years. Traditional access to the heart requires a full sternotomy, forcible spreading of the sternal margins, and entry into the pericardium. Once inside the pericardium, manual manipulation of the heart is usually necessary to reach the blocked arteries. Currently, only makeshift manipulators and retractors are available for the surgeon to use in an attempt to position the heart to facilitate surgical access. Such crude tools include surgical gloves that have been inflated and tied off prior to placement under an organ and gauze pads that are also used to shim organs into position. However use of such primitive tools presents problems such as risk that the tools will inadvertently be left behind after the procedure is complete, risk of damage to the surface of the heart or pericardium during their placement and removal and lack of ability to perform real-time control of organ elevation and position. Other balloon devices have been disclosed that assist in removal of hollow organs and that move organs and other structures, such as the abdominal wall, away from the area of surgical interest. See Moll et al, International Application No. PCTUS92/04393; this and all other references cited herein are expressly incorporated by reference as if set forth herein in their entirety.
The interior surface of the pericardium itself is a delicate, serous membrane within which the heart slides freely. Any trauma to this surface, or to the heart itself, can subsequently cause adhesions to form, and therefore any means of manipulation or retraction must be very gentle. Reoperation within the pericardium often reveals evidence of previous traumatic manipulation, such as extensive adhesions between the heart and pericardium which must be released before further manipulation can be attempted. There is presently an unfulfilled need for more sophisticated devices that will permit atraumatic manipulation and stabilization of the heart and other organs and allow the surgeon to manipulate organ positioning from outside the surgical cavity.
Situations requiring more extreme manipulation create even greater intraoperative risk such as the likelihood that heart function will be impaired, or may even cease. The extent of motion required for such functional impairment to occur varies by individual and may be due to any of several causes, including kinking of the great vessels. If the heart ceases to function, the surgeon is faced with two choices, either (1) perform cardiopulmonary bypass (CPB), stopping the heart, or (2) lessen the manipulation until function is restored. The advantage of CPB is that it maintains apparent heart function to the rest of the body and provides opportunity for temperature control of the blood and cardioplegia being infused. However, a disadvantage is the risk of blood and organ damage. Moreover, prolonged bypass of the heart can damage heart tissue. However, it is thought that maintaining the heart in a hypothermic state may limit the degree of heart muscle necrosis. While other devices have been disclosed that cool the heart (see Daily, U.S. Pat. No. 5,609,620), these devices are not capable of simultaneously lifting and positioning the heart. On the other hand, stopping the heart has the advantage of allowing the heart to be emptied of blood, thus reducing its volume. Such volume reduction may, accordingly, allow more freedom for heart manipulation within the pericardium. Given these choices, it would seem most advantageous to work within a range of manipulation in which heart function is not compromised. Although such an outcome is attractive in some ways, it complicates the surgical procedure by presenting the surgeon with a beating heart upon which to complete very intricate anastomoses. The most advantageous solution, which has been unavailable heretofore, would be to not compromise heart function, yet provide a fixed surgical surface that is not affected by heart motion. It is clear that with current techniques and tools available, no one solution is without problems, and risk of trauma to the chest, and its resulting complications, is considerable. It is not therefore surprising that the search for better methods continues.
Early techniques designed to avoid some of the drawbacks of open heart surgery led to catheter techniques that open stenotic regions and reestablish blood flow without requiring arterial grafting. This advance was successful from the standpoint that it virtually eliminated trauma and reestablished blood flow quickly. However, some stenoses are difficult to treat using this technique, and its effectiveness is of limited duration. Such limitations led to the use of stenting in an effort to prolong patency. However, even with these advances, problems exist, and therefore, the search for other solutions still continues.
The middle ground of CABG surgery, performed through minimal incisions, is now becoming attractive. CABG surgery allows alternative approaches to a full sternotomy, the traditional incision used in open heart surgery, such as (1) a partial lower sternotomy, from the xiphoid process up to the second intercostal space, terminating in a transverse division to free the sternal margins, or (2) a mini-left thoracotomy, with partial removal of the fourth, left rib. Other choices are also in use or are currently being considered. As in open surgery, manipulation of the heart is still required and in fact, as incision sizes decrease, the nature and extent of this manipulation may change, and, accordingly, the difficulty may increase. In planning such a minimal incision, the surgeon must consider not only the desired manipulation of the heart itself for access to the coronary arteries, but must also consider optimal access to vessels which will be used to bypass the occluded arteries. The only tools available for such delicate cardiac manipulation and positioning are rigid manipulators with sharp contact points that can cause tissue trauma or primitive positioning tools discussed previously such as inflated gloves and gauze pads, which, in this procedure, are even more difficult to place and remove given the smaller incision size. Similar concerns apply to cardiac valve procedures where the heart must be positioned so that the appropriate surgical tools can reach the inner structure of the heart, as opposed to its surface.
In summary, it is clear the surgeon must weigh many issues in choosing the best access for a cardiac procedure. Such issues include: (1) patient-specific anatomy, condition and disease, (2) the requirements of the intended treatment, (3) the trauma likely to result, and (4) the likely risks of complications. Moreover, any procedure selected must align with the surgeon""s own skill, knowledge, and comfort level. Any choice will involve some degree of compromise. However, the availability of better cardiac positioning and manipulation devices can expand the number of viable choices by reducing trauma to the patient and creating a surgical environment with better access and enhanced stabilization of the structures that are the subject of such delicate techniques.
Moreover, lack of such devices is an impediment to the advancement of surgical cardiac procedures. It is clear that incision size is trending downward, that future procedures may entail multiple incisions, and that, in time, xe2x80x9cportxe2x80x9d or cannula access may be the only technique used. As this reduced incision size evolves, the need for atraumatic manipulation and stabilization of the heart within the pericardium will increase markedly.
Although we have focused on the development of cardiac surgical techniques in the context of the evolution of the need for atraumatic positioning and manipulation devices, it is clear that need for such devices also exists in surgical procedures in other anatomic locations. For example, procedures that require lifting or positioning of solid organs including the liver and the spleen would be enhanced by the present invention.
Insofar as we are aware, there has been no disclosure of an inflatable manipulator that can atraumatically manipulate and stabilize organs for optional access during surgery, nor are such devices available. A need therefore exists for an inflatable organ manipulator which may include various enhancements for simultaneous organ cooling and monitoring and for dissecting adhesions, The following methods and apparatus more specifically can be used to place manipulators between the heart and the pericardium in order to manipulate and stabilize the heart""s position and orientation, and to cool it during periods of prolonged bypass.
There are three common forms of manipulation of the heart within the pericardium in open surgery when access is by means of total sternomy. Perhaps the most common is elevation of the apex or ventricle end of the heart, in the anterior or forward direction. The second most common maneuver is elevation and medial rolling of the outer or lateral (obtuse) margin of the heart. Sometimes these two maneuvers are combined. Both maneuvers are directed at reaching the extremes of the left anterior descending artery and the circumflex artery on the left side of the heart. Neither motion generally requires elevation of the medial, superior corner of the heart. A less frequent maneuver is to lift and roll the medial or acute margin outwardly to access the extremes of the right coronary artery. With use of MIS access, the maneuvers may vary from open surgery techniques depending on the orientation and proximity of the surgical site to the incision or port.
The present invention relates to inflatable manipulators for organ positioning during surgery. One organ that may be so manipulated is the heart during MIS or open surgery.
In one embodiment, where MIS is to be performed, the manipulator comprises an inflatable balloon formed from one or more flexible or elastomeric sheets enclosing one or more chambers, each chamber in fluid communication with an infusion source, and the embodiment also includes a positioning structure. In this embodiment, the positioning structure is used to insert the manipulator into position between the organ and an adjacent structure. The deflated manipulator may be compressed or rolled into a narrow shape for insertion through the smaller incision typical of MIS. Once the manipulator is in the desired position, the balloon""s chamber is inflated by infusing a liquid or gas through the infusion source until the balloon elevates and tilts the organ to the desired height and orientation. The surgical procedure is then performed on the organ. In one embodiment, liquid or gas cooled below normal human body temperature, 37xc2x0 C., can be infused into the chamber to maintain the organ at a temperature below 37xc2x0 C. and thus slow the rate of organ necrosis, for instance, during prolonged cardiac bypass procedures. In another embodiment, a sensor coupled to the balloon detects temperature, and temperature control of surfaces in contact with the balloon can be achieved. The sensor can be coupled to a computer or feedback system which provides information to a control device at the infusion source which then adjusts the temperature of the gas or liquid that is circulating through the balloon. The control device can be a pressure regulator or a mass flow controller coupled to the infusion source.
In one embodiment, the positioning structure is a pocket at the end of the balloon that is adapted to receive an insertion device. The pocket can be welded or fused to the end of the balloon. The insertion device includes a substantially tubular member curved at one end and a flexible rod that slidably inserts inside the tube and protrudes beyond the curved end of the tubular member. By sliding the flexible rod through the tube and placing it against the distal edge of the inside of the pocket, the manipulator can be advanced into the desired position inside the body cavity. Once the manipulator is in position, the insertion device is removed, leaving the manipulator in place and ready for inflation.
In certain embodiments, the positioning structure is a sheet that protrudes out from the balloon forming a flap. In some cases, the sheet is flexible and in other cases, where pushing the manipulator into place may be necessary, the sheet is relatively stiff. The sheet may be used to lift, slide or push the manipulator into position. The sheet may alternately be used to anchor the manipulator by placing the sheet under the organ upon which surgery is performed or a structure in the proximity of the organ. The sheet may be roughened to enhance traction on the organ or the adjacent structure. Such roughening can be accomplished by forming parallel ridges, dimples or blisters in the sheet or by coupling it to one-half of a hook-and-eye or Velcro(copyright) fastener pair. In one embodiment the sheet may be formed in the shape of a strap coupled along its long side to the outer surface of the balloon. Most of the coupling can be perforated so that once the manipulator is in the body cavity, the strap can be pulled away from the balloon along the perforated portion of the coupling and remain attached in the coupled region that is not perforated. This strap can then be used to further position the manipulator.
Another embodiment includes a plurality of parallel, tubular balloons joined at their outer surfaces to form a mattress. The balloons may be of equal diameter, or may be sized to result in a different vertical projection transverse to the general plane of the mattress. Although the balloons can be joined to form a single internal cavity, each balloon can be independently in fluid communication with a separate infusion source to allow independent control of the vertical projection of each balloon. In another embodiment, a large, flat balloon is internally fused in regions, or otherwise partitioned selectively, so that separate inflation of each chamber produces a contoured surface on the manipulator.
In certain embodiments, multiple balloons are arranged such that parts of each balloon overlap the other. These balloons can be fashioned out of more than two flexible sheets, or can be molded with internal partitions. The separate chambers can be connected to a single infusion source or can be connected to independent infusion sources. This embodiment is useful where the apex of the heart is to be lifted independently, the left or obtuse margin is to be lifted independently, or both the apex and the previously-described margin are to be lifted concurrently. In another embodiment, two balloons are formed in an inverted xe2x80x9cLxe2x80x9d shape and overlap at their common comer. This embodiment is placed such that the two xe2x80x9clegsxe2x80x9d of the xe2x80x9cLxe2x80x9d underlie the inferior and lateral regions of the heart, so that inflation of the inferior balloon would elevate the apex of the heart while inflation of the lateral balloon would roll the obtuse margin of the heart in a superior medial direction. When both balloons are inflated, a combined motion of apex lifting and medial rotation is achieved. Alternately, if the manipulator is placed with the balloon xe2x80x9clegsxe2x80x9d inferior and medial, access to the extremities of the right coronary artery can be achieved.
In another embodiment, where open cardiac surgery is to be performed, the manipulator comprises an inflatable balloon enclosing a chamber in fluid communication with an infusion source, and a relatively rigid platform which can be welded or otherwise fused at its perimeter, or near its center, to the balloon. In its simplest form, the balloon is a pillow-shaped, single-chamber balloon. The relatively rigid platform aids in insertion of the balloon under the organ to be lifted and in stabilizing the manipulator once it is in place. Once in position, the balloon is inflated through the infusion source to position the organ and surgery is performed.
Other embodiments include balloons that are partitioned by selectively fusing various regions of the balloon inner surface to produce more than one chamber where each chamber is in fluid communication with a separate infusion source. In other embodiments, two or more balloons are coupled to one another and can be coupled to the relatively rigid platform. By providing these combinations of chambers and balloons, various orientations of the organ can be achieved by selectively infusing each chamber or balloon with gas or liquid to the desired degree of inflation.
After inflation, balloons can assume a variety of shapes depending upon their construction including rectangular, spherical, oblong, tubular, triangular, toroid, annular or concave. The relatively rigid platform also be a variety of shapes including trapezoidal, triangular, square, rectangular, circular, oval and oblong. The relatively rigid platform may also be wedge-shaped and molded of polyurethane, silicone or medical grade foam and can include embedded balloons that expand away from the surface of the platform. This structure has the advantage of preventing balloon slippage during inflation and creating more precise positioning of the balloons on the platform during fabrication.
In other embodiments, various structures may be attached to the relatively rigid platform or to the outer surface of the balloon to aid in positioning or stabilizing. Such attached structures include flexible elongated members and sheets made of flexible or elastomeric material that serve as anchoring flaps. In one embodiment, the flexible elongated members may be fitted with a hole at the unattached end of each member. The hole may be used to attach the member to a flexible cord, including, but not limited to, suture material, so that the cord may be used to lift various edges of the relatively rigid platform to assist in properly positioning the organ or may be used to anchor the member to adjacent tissue. The members may be used to lift portions of the relatively rigid platform. In the embodiment where the attached structure is a sheet that extends out from the balloon forming a flap, such sheet may also be used to lift a portion of the balloon or the relatively rigid platform for better positioning. The sheet may alternatively be used to anchor the platform by placing such sheet under the organ or an adjacent structure in the proximity of the organ upon which surgery is performed. In one embodiment, a strap may be fashioned from the sheet and attached to the balloon or to the relatively rigid platform. In another embodiment, the attachment of the sheet or strap may be partially perforated, so that most of the sheet or strap may later be torn away and used for manipulation.
In another embodiment, a plurality of inflatable balloon pillars are coupled to a relatively rigid platform. The height of all balloons can be controlled by a single infusion source if uniform elevation of the organ is desired, or alternatively, each balloon can be controlled independently to give the surgeon intraoperative control of elevation of various regions of the organ.
One method of fabrication of balloons for this invention is the bonding or welding together of flat, polymeric sheets. Other methods include molding or dipping to form elastomeric balloons. Useful polymeric balloons can also be structured to change shape upon increasing inflation by selective yielding of portions of the balloons. For example, if balloons are constructed of multiple flat, flexible sheets of polymeric material, a weaker or thinner sheet will yield in preference to a stronger or thicker sheet. In this manner, a single chambered balloon might be flat during initial inflation, as constructed, and upon appropriate inflation, will assume a banana or crescent shape. The creation of the curved aspect can be accomplished during manufacturing, or, alternately during deployment and inflation within the patient. Similar results can also be achieved by blow molding chambers with eccentricity between the outer diameter and the inner diameter which results in unequal wall thickness.
By their nature, balloons can be designed to be quite hard and unyielding. However, for this invention, they are constructed in a manner that produces soft exteriors covering a large surface area, and are further designed to be compliant to accommodate the varying topography of the adjacent structures. Since sharp edges on the balloons may be trauma-producing, balloons fabricated from flexible sheets can be constructed by inverting the edges to avoid creation of sharp external edges that would result from welding or bonding where such external edges could come into contact with the heart or pericardium.
Since the objective of these heart manipulations is to present different areas to the surgeon for bypass surgery, it may be inconvenient if the balloon covers the particular surface segment which is the desired surgical site. Multiple chambered balloons are advantageous to overcome this problem, because they allow the surgeon to deflate part of the balloon at will to obtain the access needed, while still maintaining inflation in adjacent areas of the balloon for the necessary""support of the heart.
In order to further enhance the usefulness of the balloon designs outlined above, appendages or collateral features are advantageous. For example, roughening of the balloon outer surface can be used to increase friction of the balloon on the adjacent anatomic structure and prevent relative movement, for instance, between the heart and balloon or between the balloon and pericardium during surgery.
Adjacent sheets or straps made from a sheet can also be used to anchor the balloon in place. For example, if a flat sheet is attached to the balloon and trapped under the heart, the friction generated by the weight of the heart can be used to anchor the balloon. Alternately, if suture material or clamps are fastened to the sheet, these appendages can similarly be used to anchor the manipulator. In one embodiment, sheets, strings or straps are attached to the outer surface of the balloon and passed out of the body cavity through the incision""so that the sheets, strings or straps can later be used for manual manipulation, somewhat in the manner of the heart net devices used currently. These sheets, strings or straps can be attached to the outer surface of the balloon with perforated connection so that the sheets can be used during placement of the manipulator, and later, they can be partially or totally detached by pulling apart the perforations. In another embodiment, they may simply be left to pass out of the body through the incision during surgery and may later be used during retractor removal.
Prior to this invention, the common technique for organ positioning during surgery was to inflate and tie off surgical gloves, then place the inflated gloves under the organ. One of the many problems with this procedure was that degree of inflation had to be estimated before placement and could not be adjusted thereafter without removal of the glove. This invention allows real-time control of inflation and varying inflation techniques which can be of great assistance to the surgeon during certain procedures. For instance, in one embodiment, inflation can be applied with slowly increasing amplitude after placement of the manipulator under the heart to allow the surgeon to cease inflation before heart function is compromised and to signal the need for initiation of CPB. In this manner, limits of safe manipulation may be assessed and tailored to the needs of the individual patient. Suitable means of inflation include squeeze bulbs, syringes, or powered pumps. Inflation can be manually controlled by the surgical team, or mechanized for inflation in a predetermined manner or to a predetermined level.
In multiple chamber or multiple balloon constructions as outlined above in various embodiments, timing and sequencing of chamber filling can produce various compound actions, such as first lifting the obtuse margin of the heart, then subsequently rolling the heart medially. Such embodiments involving multichamber or multi balloon inflation sequencing can enhance the positioning maneuver compared to positioning achieved by a single chamber or a single fill alternative. In another embodiment, the lifting of a lower chamber can raise the heart to a position level with a lateral chamber which can subsequently be inflated, providing control which would otherwise be unavailable with a single chamber, single fill embodiment.
Use of real-time inflation also allows the possibility for sequencing balloon inflation and deflation to counteract the motion of a beating heart, leaving the surgical surface in a fixed position. Compensating for movement and providing a stable surface greatly enhances the surgeon""s ability to perform delicate techniques. To accomplish this compensating movement, in one embodiment, open-loop or closed-loop feedback control is applied to chambers of support balloons where each balloon""s inflation is individually controlled by computer in response to feedback from sensors such as a linear, variable differential transformer (xe2x80x9cLVDTxe2x80x9d), or other such devices which are attached to the heart along various axes. If, for example, the sensor is located near the point of anastomosis, the motion in that vicinity might be essentially stopped, making the anastomosis much easier even though the heart continues to beat.
The size of the incision and its position relative to the area of surgical interest within the body cavity affect the difficulty of placement of the manipulator in the desired location. The methods of the present invention include a variety of placement techniques. In certain cases, there may be room for the surgeon""s hand to displace the heart in order to facilitate insertion of the balloon. In other cases, forceps or laparoscopic graspers can be used, such as a xe2x80x9cRoticulatorxe2x80x9d grasper (United States Surgical Corporation). In the embodiments where the manipulator includes a relatively rigid platform, the rigidity of the platform will assist in insertion and further enhances reaching areas not accessible to the surgeon""s hand, even if the platform is a foam structure.
In cases where the incisions are very small, or where cannulae are used, insertion may require the balloon be compacted and retained for insertion and placement purposes, then released prior to or during inflation. The methods of Kieturakis, et al., U.S. Ser. Nos. 08/483,293 and 08/484,208 are hereby incorporated by reference. For these small incision procedures, a particularly useful embodiment includes a balloon formed from one or more flexible sheets forming one or more chambers or one or more balloons each in fluid communication with an infusion source and also includes a positioning structure to allow placement via insertion device. In one embodiment, the positioning structure is a pocket provided at the distal end of the balloon adapted to capture the distal end of an insertion device, which device is then removed prior to or during inflation of the balloon. For example, see commonly assigned, co-pending application U.S. Ser. No. 08/815,398, now U.S. Pat. No. 6,004,340, which is hereby incorporated by reference.
In one embodiment, the insertion device is a substantially rigid tubular member which is curved at its distal tip to advance the manipulator as far as possible in the direction of desired insertion. A flexible rod slides Inside the tube and engages the pocket on the balloon. In one embodiment, the flexible rod is made of rubber and in another embodiment it is made of Nitinol. The rod extends slightly beyond the tube to engage the pocket, and the balloon is staged along the tube and rod. In positioning manipulators for cardiac surgery, the insertion device and manipulator are advanced to the point where the curvature of the tube is at the maximum heart curvature, and the rod is then advanced relative to the tube, carrying the balloon further around the curvature of the heart. When the balloon is properly positioned, the rod is withdrawn into the tube, and the rod and tube withdrawn from the incision. The withdrawal of the insertion device can be concurrent with initiation of balloon inflation. The reach of the insertion device can be further extended if the rod is itself curved where it extends beyond the tip of the tube.
In one method, the manipulators are used to release adhesions between adjacent tissue structures, such as adhesions that may form between the heart and the pericardium. Such release can be accomplished either by using the manipulator to stretching the adhesions to facilitate exposure for sharp dissection, or by using the manipulator to actually pull apart adhered layers. This latter method can only be used where there is no danger of tearing in an unintended structure.